1. Field of the Invention
The present invention relates to novel liquid dielectric compositions and, more particularly, to liquid dielectrics comprising [1] a liquid dielectric component of a type known to be useful for its electrical insulation properties, in combination with [2] at least one member selected from the group consisting of monocyanophenoxybenzene, monocyanodiphenyl and monocyanoterphenyl. These liquid dielectric compositions find use as insulators of electrical equipment generally, especially of transformers and capacitors.
2. Description of the Prior Art
The prior art recognizes various dielectric materials to be used, for example, as insulation for electrical equipment. The primary characteristics considered essential to the proper functioning of such dielectrics include high permittivity, low initial conductivity, good thermal stability, e.g., a high resistance to thermal decomposition upon aging, low vapor pressure, low freezing point, and the like. Many materials have heretofore been employed as dielectric liquids, either alone or in admixture, and include mineral oil, chlorinated diphenyl, certain esters of organic acids, castor oil, aromatic hydrocarbons and the alkylates thereof, and the like. These compounds and compositions have been found to display the necessary characteristics permitting their use as electrical insulators. Few of such compounds and/or compositions, however, exhibit the aforesaid requisite properties while at the same time permitting individual parameter optimizations thereof. For example, those dielectric liquids which are known to the art and which possess the requisite properties of low conductivity and/or thermal stability or resistance to thermal degradation, have generally been found to display a permittivity which is too low, at least for certain applications.